mystery (Glaucous-thing) gull


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Posted by Phil Pickering (208.46.229.117) on August 07, 2000 at 15:26:08:

The head and bill-shape, and chesty look seem to rule
out Iceland, leaving a Glaucous or a faded Glaucous-winged as the main possibilities (barring something albinistic, which I have no experience with).

I would lean toward Glaucous on this one. I was able
to enlarge the scan and the iris is actually medium-
pale brownish at the very least (may be pale yellow,
but appearing darker due to being in shade). This
doesn't rule out Glaucous-winged, but it is suspicious
for a bird that apparently has white primaries. Based on this one photo the primaries look like they are supposed to be white to me. In my experience an older (3rd or 4th-year) GW will tend to have a dingy or dirty look to the primaries when they are faded or worn whitish. The whitish outer primary edges tend to fade gradually into adult gray. This photo may be misleading me, but I don't see any intermediate dingy coloration in the primaries of this gull. There is one inner primary visible where the whitish edge borders the adult gray color without much in the way of intermediate tones, as it should in an adult or near-adult Glaucous. It also looks like there is too much whitish coloration in the tertials for a GW of this age. I would expect to see more intermediate grayish coloration there also if this were a faded/worn near-adult GW. Something about the pattern and coloration of wear and molt in the coverts also suggests Glaucous to me, not sure what. The primary projection is extreme for either species, but may be within the range of barrovianus Glaucous. I think the bill-shape is also within the range of barrovianus Glaucous (based on my limited experience). Also, I would say the pattern on the bill-tip might favor Glaucous - the black on the tip seems to be fading very cleanly, and also evenly on the upper and lower mandible (changing to red on the lower) with very little, if any, coloration inward beyond the gonys. Lastly a minor point that may not mean much, but my impression is that the raised area around the eye tends to be a bit more pronounced in Glaucous than in GW at all ages, and it appears to really stand out on this gull, which looks quite "eye-ringed". I agree with Steve Hampton that the mantle-shade appears too dark for Glaucous, but I'm wondering if this also isn't a result of it being mostly in shade (and I also know from experience that smithsonianus Herring often look much darker-mantled in photos than in life).

Photos can fool, hopefully I'm not being fooled too badly by this one!
Thanks,

Phil Pickering
Lincoln City, Oregon



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